Honeycomb: Area containing primarily coarse aggregate
Voids: Areas containing no concrete

Honeycomb forms when mortar fails to fill voids between coarse-aggregate particles. The defect may be purely cosmetic or, depending on the location and extent of honeycombing, may be structural and require repair. For instance, honeycombing behind posttensioning anchors may require repair so the post tensioning forces don’t cause compressive failure of concrete in the bearing area .